Fence charger



Jan. 14, 1969 E. w. OLSON 3,422,280

FENCE CHARGER Filed Aug. 19, 1965 Sheet of 2 INVENTOR. [1.415 M 0150 4 Tramway:

Jan. 14, 1969 w OLSON 3,422,280

FENCE CHARGER Filed Aug. 19, 1965 Sheet 2 of 2 United States Patent 3,422,280 FENCE CHARGER Ellis W. Olson, Hopkins, Minn., assignor, by mesne assignments, to Introl Corporation, a corporation of Minnesota Continuation-impart of application Ser. No. 351,033, Mar. 11, 1964. This application Aug. 19, 1965, Ser. No. 483,016 US. Cl. 307-132 4 Claims Int. Cl. H01h 47/00; 51/34; H02j This is a continuation-in-part of my pending application for US. Letters Patent, Ser. No. 351,033 filed Mar. 11, 1964, now abandoned, for fence charger.

This invention relates generally to electric fences and is more particularly directed to electrical fences in which the operation is characterized by the use of a periodically occurring pulse of electrical energy of suitable magnitude.

In the prior art with which my invention is concerned, electrical fences comprised of a single conductor mounted upon suitable posts and insulated from ground is energized from a source of electrical pulses of suitable energy content that is connected intermediate the conductor and ground whereby objects, such as animals, serve to complete an electrical circuit between the conductor and ground and are thus repelled from the fence and contained within an area surrounded by the fence. In the prior art apparatus, various means are utilized for providing periodic pulses of electrical energy including relays, motors operating mechanical contacts, pendulums and various other electromechanical devices. Experience has shown that the prior art devices tend to be short-lived and unreliable in operation and therefore require the attention and supervision of an operator during operation at various intervals dependent upon the character of the apparatus used. Some of the prior art apparatus has proven expensive to manufacture and where the initial cost of producing the apparatus has been successively reduced to a relatively low value, increased costs of operation and maintenance have resulted.

As will be explained in more detail below, my invention provides an improved electrical fence in which electrical energy is accumulated in a capacitor during intervals in which an asymmetrical signal responsive current controlling means effectively isolates the conductor on an electrical fence from the electrical energy being stored in the capacitor and which is responsive to a signal provided by means responsive to the potential of the energy stored in the capacitor to render the signal responsive current controlling means conductive to thereby discharge the energy stored in the capacitor to the conductor on the fence. Suitable electrical energy transforming means may be utilized to modify the potential and current magnitude of the energy supplied to the fence conductor and applied intermediate the fence conductor and ground or earth.

My invention further provides improved means for preventing the application of a high current low potential output on the fence enclosure conductor. Briefly, this feature of my invention utilizes a potential responsive current conducting device connected in shunt with a further device having a substantially high impedance to current flow therethrough. When a relatively low potential is applied to the fence conductor, the current limiting impedance reduces the current flow to a safe value which will not harm livestock, or like objects coming into contact with the fence conductor. The level of potential at which the potential responsive current conducting device is operative to shunt the flow of electrical energy around the current limiting impedance is higher than the source of electrical energy to which the fence controller apparatus is connected. The level of potential normally supplied to the fence conductor is further substantially higher than the source of electrical energy to which the fence controller is connected. It may thus be seen that the current limiting impedance is connected in circuit with the output of the fence controller and the fence conductor and is shunted by the potential responsive current conducting device when a pulse from the fence controller having sufiicient potential magnitude is applied and the entire apparatus is operative as normally desired. However, should a short circuit, or the like, occur in which the source of electrical energy may be directly connected to the fence conductor, the potentially lethal amount of electrical energy is reduced to a harmless safe level by virtue of the fact that the current limiting impedance is present in the circuit and the potential of the supply of electrical energy does not exceed the operating level of the potential responsive current conducting device.

It is therefore an object of my invention to provide an improved electrical fence of the type in which periodic pglses of energy are utilized to repel animals and the li e.

Another object of my invention is to provide an improved source of uniform pulses of electrical energy for use in combination with an electrical barrier fence.

A further object of my invention is to provide a more reliable source of energy for an electrical fence.

A further object of my invention is to provide a longer lived source of energy for an electrical fence.

A still further object of my invention is to provide a source of energy for an electrical fence which is automatic in operation and does not require the use of any mechanical moving elements.

Another object of my invention is to provide an improved source of energy for an electrical fence in which capacitive electrical energy storing means, signal means responsive to the potential on said capacitor means and signal responsive current controlling means are utilized in cooperative relationship to provide uniform periodic pulses of electrical energy to an electrical fence.

It is a still further object of my invention to provide improved fence charging apparatus having an increased safety factor in operation.

A further object of my invention is to provide an electric fence charging circuit in which the current flow is substantially reduced for potentials below a predetermined normal level of operation of a fence charger.

A still further object of my invention is to provide potential responsive current limiting means connected in series with the conductive portions of a fence charging circuit.

These and other objects of my invention will become apparent from a consideration of the appended specification, claims and drawings in which:

FIG. 1 is an electrical schematic and diagrammatic drawing of a preferred embodiment of my invention; and

FIG. 2 is a similar diagrammatic and schematic drawing of the preferred embodiment of my invention and includes a potential responsive current limiting device.

Referring now to FIG. 1 of the drawings, there is shown an electrical fence indicated generally by the reference character 10 which is comprised of a single conductor 11 that is supported at appropriate intervals on a plurality of insulators 13, each mounted on a suitable support post 12. A pair of output terminals 14 and 15 are shown connected to the secondary winding 18 on transformer means 16 through conductors 19 and 20 respectively. Terminal -14 is connected to conductor 11 and terminal 15 may be connected to a suitable ground as indicated by reference character 40. In the class of electrical fences with which my invention is concerned, terminals 14 and 15 are supplied with periodic pulses of electrical energy of suitable potential and current magnitude for repelling animals and the like from contact with conductor 11 when a circuit from ground is completed through the object to conductor 11. A resistor 21 and indicator lamp 22 are connected in parallel with secondary winding 18 to provide a visual indication of the presence of an energy pulse across the secondary winding 18.

Primary winding 17 on transformer 16 is adapted to be energized with periodic pulses of energy from a capacitor 39. Capacitor 39 is connected in parallel with primary winding 17 on transformer 16 in a circuit proceeding from the top end of primary winding 17, through conductor 30, capacitor 39, conductor 31, cathode 34 and anode 33 on a signal responsive controlling means shown in the form of silicon controlled rectifier 32, and conductor 36 connected to the bottom end of primary winding 17. Trigger electrode 35 on silicon controlled rectifier 32 is connected to the top end of transformer winding 17 through a potential responsive signal means 38 shown in the form of a Zener diode. A further asymmetrical current conducting device 37 is shown connected in parallel with transformer primary winding 17 and is provided to form a circuit for shunting the current resulting from collapse of the magnetic field present in transformer 16 after a pulse of energy has been applied thereto.

Capacitor 39 may be energized from a pair of input terminals 23 and 24 adapted for connection to a suitable source of alternating current energy (not shown) through a circuit including conductor 25 connected to terminal 23, asymmetrical current conducting device 26, resistor 27, capacitor 39, and conductor 31 connected to terminal 24. A resistor 28 and visual indicator lamp 29 are shown connected in parallel with resistor 27 to provide a visual indication of the operation of my invention.

-In the embodiment shown, capacitor 39 is charged at a rate, dependent upon the value of resistor 27, with pulses of unidirectional current through asymmetrical current conducting device 26 which are derived from the alternating current energy applied to terminals 23 and 24. At the time the energy stored in the capacitor 39 attains a predetermined magnitude which is proportional to the potential thereacross, the potential responsive source of signal, shown as Zener diode 38, provides a signal in the form of a current to trigger electrode 35 on silicon controlled rectifier 32. The application of a signal to trigger electrode 35 on silicon controlled rectifier 32 renders it conductive whereby the energy stored on capacitor 39 is discharged through transformer primary winding 17 and silicon controlled rectifier 32 to provide an output pulse of uniform energy content and of a predetermined potential and current magnitude dependent upon the characteristics and values of the various elements of which my invention is comprised. Transformer 16 serves to modify the potential or current magnitude of the pulses in a manner well known to those skilled in the art and which will depend upon the desired characteristics of the pulses of electrical energy applied to electrical fence 10.

In the operation of my invention, it will be assumed that capacitor 39 is initially discharged, that it is in a condition wherein no potential exists thereacross. Terminals 23 and 24 are connected to a suitable source of alternating current energy and pulses of unidirectional electrical energy will be supplied to capacitor 39 through resistor 27. During this time, indicator lamp 29 will indicate that capacitor 39 is receiving a charge of electrical energy as indicator lamp 29 will be energized as long as a current is flowing through resistor 27. As a charge of electrical energy is built up across capacitor 39, the potential appearing at conductor 30 will gradually increase to a value approaching the potential of the unidirectional pulses applied to capacitor 39 During the time a charge is being accumulated across capacitor 39, silicon control-led rectifier 32 remains nonconductive so that none of the electrical energy content of the unidirectional pulses applied to capacitor 39 is present across primary winding 17 on transformer 16.

When the potential across capacitor 39 rises to a predetermined value dependent upon the characteristics of Zener diode 38, a small current will be conducted through Zener diode 38 in the reverse direction and to trigger electrode 35 on silicon controlled rectifier 32. The application of the current to silicon controlled rectifier 32 renders it conductive to complete a circuit from the top end of capacitor 39 to its lower end through conductor 30, transformer primary winding 17, conductor 36, anode 33, cathode 34 and conductor 31. When the potential across capacitor 39 and thereby across silicon controlled rectifier 32 reaches a predetermined minimum value, silicon controlled rectifier 32 is rendered non-conductive and because Zener diode 38 is likewise rendered non-conductive by the absence of a potential exceeding a predetermined value thereacross, the circuit for dissipating the charge on capacitor 39 is interrupted.

The fiow of current through transformer primary winding 17 serves to provide a corresponding current of higher or lower magnitude across secondary winding 18 which is in turn applied to output terminals 14 and 15 connected to provide the pulse of electrical energy to electrical fence 10. During the time a pulse is applied to output terminals 14 and 15, indicator lamp 22 will provide a visual indication thereof.

As the field in transformer 16 collapses after the circuit for dissipating the charge on capacitor 39 has been interrupted, the energy created thereby is shunted through asymmetrical current conducting device 37 connected in parallel with transformer primary Winding 17.

Immediately upon interruption of the circuit for dissipating the charge on capacitor 39, current is again applied thereto to build up a charge in the manner first described and periodic application of pulses of uniform energy content to electrical fence 10 is provided.

The frequency of operation of my improved electrical fence is determined by the values of resistors 27 and 28 and capacitor 39. Suitable values for these and other components may easily be determined by those skilled in the art for specific applications of my invention.

Referring now to FIG. 2 of the drawings in which like elements have been identified with like reference characters, it may be seen that the circuit connecting secondary winding 18 on transformer 16 includes a current limiting impedance, shown in the form of resistor 41, connected intermediate the lower end of secondary winding 18 and conductor 20 that is in turn connected to output terminal 15. A potential responsive current conducting means is indicated generally by reference character 44 and, in the embodiment shown, is comprised of a pair of Zener type diode rectifiers 42 and 43 connected in opposing or backto-back relationship. Current conducting device 44 is shown connected in parallel with impedance means 41. In one operative embodiment of my invention in which the source of alternating current energy to which the apparatus was connected was of the magnitude of volts, satisfactory operation was obtained with a value of 100,000 ohms for impedance means 41 and a potential responsive current conducting device designed to be rendered conductive by the application of a potential of approximately 200 volts thereacross.

Operation Under normal conditions of operation, the potential supplied to the conductive portion of an electric fence is relatively high and is always substantially higher than the source of electrical energy from which the charger, or controller, is energized. In the embodiment of FIG. 2 of the drawings, the potential appearing across secondary winding 18 on transformer 16, under normal operating conditions, is always higher than the potential of the source of electrical energy and the level of potential at which current conducting device 44 is designed to become conductive is selected to lie somewhere between the potential of the source of electrical energy and the potential that is normally supplied to the fence conductor. Therefore, when the controller is operative under normal conditions, each time a pulse of electrical energy is supplied to transformer 16, a resulting relatively high potential appearing across secondary winding 18 is sufficient to render current conducting device 44 conductive to form a shunt around current limiting impedance means 41, and there is no substantial eiiect on the operation of the apparatus by the addition of this feature of my invention to an electric fence controller. However, should a short circuit to ground occur (such as the housing for the fence charger) in the components connected to the primary winding of transformer 16, or if for any other reason, the source of electrical energy should become directly connected to transformer secondary winding 18, current conducting de'vice 44 will remain non-conductive and current limiting impedance 41 will limit the flow of current at the relatively low potential to a safe, non-lethal magnitude.

It is understood that suitable modifications may be made in the structure as disclosed, provided such modifications come within the spirit and scope of the appended claims.

Having now therefore fully illustrated and described my invention, what I claim to be new and desire to protect by Letters Patent is:

1. In combination with an electrical fence controller of the class to be operated from a source of alternating current potential and including a pair of input terminals adapted to be connected to a source of alternating current potential of relatively low magnitude, means for periodically providing pulses of electrical energy of a relatively high potential across a pair of output terminals adapted to be connected intermediate a ground terminal and the conductive portion of an electric fence, a current limiting impedance means, having potential respon sive current conductive means connected in parallel therewith, connected in series with said output terminals on a fence controller.

2. The apparatus of claim 1 in which the impedance means is a resistor and the potential responsive current conducting means is comprised of a pair of Zener diodes connected in opposed relationship.

3. An electric fence charger comprising in combination: a source of unidirectional current, said source of current including first and second terminals; circuit means connecting the extremities of a capacitive means to said first and second terminals respectively; current controlling means having input, gate and output electrodes, said current controlling means being conductive only when its input, gate and output electrodes are concurrently energized; circuit means connecting the input and output electrodes of said current controlling means to the respective extremities of said capacitive means, said circuit means including a pair of load terminals, one of said lead terminals including current limiting impedance means, having potential responsive current conducting means connected in parallel therewith, said load terminals being adapted for connection to an electric fence; means responsive to the presence of accumulated energy in excess of a predetermined quantity to provide an output in accordance therewith; and circuit means connecting said last named means between one extremity of said capactive means and the gate terminal on said current controlling means whereby said current controlling means is rendered conductive to allow energy to flow between the extremities of said capacitive means.

4. An electric fence charger comprising in combination: a pair of input terminals adapted to be connected to a suitable source of alternating current; capacitor means having first and second terminals, trans-former means having a primary and a secondary winding; circuit means, including a current limiting means, having a potential responsive current conducting means connected in parallel therewith, connecting said secondary winding between a ground electrode and a conductor on an electric fence; a Zener diode having cathode and anode electrodes; a silicon controlled rectifier having cathode, anode and gate electrodes; circuit means, including asymmetrical current conducting means and resistive means, connecting the first terminal on said capacitor means to one of said input terminals; circuit means connecting the second terminal on said capacitor means to the other of said input terminals; circuit means, including said primary winding, conmeeting the anode and cathode electrodes on said silicon controlled rectifier in series with the first and second terminals, respectively, on said capacitor means; and circuit means connecting the cathode electrode on said Zener diode to the first terminal on said capacitor means and the anode electrode thereof to the gate electrode on said silicon controlled rectifier.

References Cited UNITED STATES PATENTS 3,302,128 1/ 1967 Schomehl et al. 3,396,946 12/1945 Kneisley et a1. 307-132 X 2,443,232 6/1948 Fagan 307132 X 3,115,610 12/1963 Begium 256-10 X 3,198,989 8/1965 Mahoney.

OTHER REFERENCES Notes on the Application of the Silicon Controlled Rectifier, General Electric, ECG-3714, December 1958, p. 36.

ROBERT K. SCHAEFER, Primary Examiner.

T. B. JOIKE, Assistant Examiner.

US. Cl. X.R. 

1. IN COMBINATION WITH AN ELECTRICAL FENCE CONTROLLER OF THE CLASS TO BE OPERATED FROM A SOURCE OF ALTERNATING CURRENT POTENTIAL AND INCLUDING A PAIR OF INPUT TERMINALS ADAPTED TO BE CONNECTED TO A SOURCE OF ALTERNATING CURRENT POTENTIAL OF RELATIVELY LOW MAGNITUDE MEANS FOR PERIODICALLY PROVIDING PULSES OF ELECTRICAL ENERGY OF A RELATIVELY HIGH POTENTIAL ACROSS A PAIR OF OUPUT TERMINALS ADAPTED TO BE CONNECTED INTERMEDIATE A GROUND TERMINAL AND THE CONDUCTIVE PORTION OF AN ELECTRIC FENCE, A CURRENT LIMITING IMPEDANCE MEANS, HAVING POTENTIAL RESPONSIVE CURRENT CONDUCTIVE MEANS CONNECTED IN PARALLEL THEREWITH, CONNECTIVE IN SERIES WITH SAID OUTPUT TERMINALS ON A FENCE CONTROLLER. 